The type of pneumatically controlled rotary actuator taken into consideration comprises substantially a body forming a first chamber and a second chamber with planes at right angles, with the first chamber practically tangent to the second chamber, where a pneumatic piston subject to alternating movements is housed, and in the second chamber is also housed and supported a rotating cogged pinion with an item holder device, and where the piston has a rack cogged attachment designed to engage with the pinion to turn the latter together with the item holder device in response to the alternating movements of the piston.
According to the known technique, the cogged pinion for such an actuator is made out of a single piece through mechanical machining and precision cogs on machine tools.
Evidently, this machining procedure of the pinion necessitates considerable time and is costly, which are further increased if you consider that in order to ensure the required resistance under force and the wear on its cogs, the pinion must be made out of a material with very high mechanical properties and hardness, therefore in itself relatively precious and costly. More often also, the item holder device is an integral part of the pinion therefore it also has to be made of the same material as the pinion and machined at the same time.
According to the state of the technique, the construction of a pinion structure with, instead of the traditional radial cogs, has pins positioned and held between two head flanges and spaced at angles around a rotation axis, is also known, in that it was proposed by the same applicant. However, on the one hand, also in this case the flanges were made by machining items made of a high strength material such as steel, the same being valid for the pins but, on the other hand, such a pinion structure has never been used in rotary actuators.